What is a Turing Machine?

Are the Turing Machines described by Alan Turing and Sir Roger Penrose the same?

Is my desktop computer or my laptop a Turing Machine?

Is the human brain a Turing Machine?

Where can I find the paper that Alan Turing wrote in which he described his Turing Machine?

Isn't the Turing Machine the computer that Alan Turing invented to crack the German Enigma during World War II?

All of the above questions are about Turing Machines in general. May I ask some questions about the Turing Machine that comes with this website?

I have a question I would like to ask, but it's not on this list.